Search results for "transistors"

Synthesis of Graphene Nanoribbons by Ambient-Pressure Chemical Vapor Deposition and Device Integration

2016

Graphene nanoribbons (GNRs), quasi-one-dimensional graphene strips, have shown great potential for nanoscale electronics, optoelectronics, and photonics. Atomically precise GNRs can be "bottom-up" synthesized by surface-assisted assembly of molecular building blocks under ultra-high-vacuum conditions. However, large-scale and efficient synthesis of such GNRs at low cost remains a significant challenge. Here we report an efficient "bottom-up" chemical vapor deposition (CVD) process for inexpensive and high-throughput growth of structurally defined GNRs with varying structures under ambient-pressure conditions. The high quality of our CVD-grown GNRs is validated by a combination of different …

Electrical and optical properties of Graphene Field-Effect Transistors (GFETs) fabricated on sapphire

Fabrication and analysis of the layout impact in Graphene Field Effect Transistors (GFETs)

2016

In this work we focused on the analysis of Graphene Field Effect Transistor (GFET) microwave parameters dependence on geometries. In particular, a statistical, experimental investigation of the cut-off frequency (ft) dependency on both the gate-drain/source distance (Δ) and the gate length (Lg) was carried out. 24 GFET families on the same chip were fabricated, each one made of 10 identical (same geometry) devices. The analysis of the measured data shows that ft is both Δ and Lg dependent, and that there exists an optimal region in Δ and Lg design space.

Microwave parameters dependence on Graphene Field Effect Transistors (GFETs) dimensions

2016

Graphene is a relatively new material whose unique properties have attracted significant interest for its use in electronic and photonic applications. In particular, field effect has been proved in graphene samples and this feature, together with the high carrier mobility observed, makes graphene an interesting solution for high frequency electronics. In our work, we performed a statistical analysis in order to evaluate the microwave parameters dependence on Graphene Field Effect Transistors (GFETs) dimensions. In more detail, for the first time, we studied the behavior of the cut-off frequency (ft) and of the output impedance (Zout) at varying both the gate-drain/gate-source distance (Δ) a…

Impact of GFETs geometries on RF performances

2016

Graphene is a relatively new material whose unique properties have attracted significant interest for its use in electronic and photonic applications. In particular, field effect has been proved in graphene samples and the observed high carrier mobility makes graphene an interesting solution for high frequency electronics. In this work, we focused on the analysis of microwave parameters dependence on geometries in Graphene Field Effect Transistors (GFETs). In particular, a statistical, experimental investigation of the cut-off frequency (fT) and of the output impedance (Zout) dependency on both the gate-drain/source distance (Δ) and the gate length (Lg) was carried out. 24 GFET families wer…

Infrared detection in multifunctional graphene-based transistors

2016

In the last years great attention has been paid to graphene-based devices for optoelectronic applications such as photodetection. In this work, we report on Graphene Field Effect Transistors (GFETs) photoelectrical response due to the photo-transistor effect. Photoelectrical measurements were performed using a 1.55 μm erbium fiber laser. Optical measurements as a function of both the incident laser power and the DC bias of the fabricated devices have been carried out and show that photocurrent increases with the power of the IR beam illuminating the sample.

Radiofrequency performances of different Graphene Field Effect Transistors geometries

2016

In this work, we investigated on microwave parameters geometry dependence in Graphene Field Effect Transistors (GFETs). A DC and RF characterization of the fabricated GFETs has been performed. The parametric analysis was carried out on 24 GFET families fabricated on the same chip and differing only for the channel length (Δ) and the gate length (Lg). In order to obtain a statistical average, each family included ten devices with the same geometry.Our study demonstrates that the output resistance and the cut-off frequency depend on both Δ and Lg. As expected, Rout increases with the graphene channel surface thus confirming the good quality of the fabrication procedures. An optimum region whi…

Photocurrent generation in Graphene Field Effect Transistors (GFETs)

2016

In this work, we focused on the study of Graphene Field Effect Transistors (GFETs) photoelectrical response due to the combination of photovoltaic and photo-thermoelectric effects. The technological steps for the transistors fabrication together with their electro-optic response will be presented. Measurements were performed by using a 405 nm laser diode with AM modulation at 1.33 KHz shined onto the sample under test. GFETs electrical output signals were measured by using a lock-in amplifier synchronized to the same reference frequency of the laser driver. This gave us the possibility to evaluate the optical characteristics as a function of both the incident laser power and the static pola…

Photoelectrical response of Graphene Field Effect Transistors (GFETs)

2016

In this work, we present Graphene Field Effect Transistors (GFETs) with photoelectrical response due to the photovoltaiceffect. Our final aim is to use a GFET to down convert an optical to a radiofrequency signal. The technological steps used for the devices fabrication as well as the photoelectrical characterization will be reported. Photoelectrical measurements were performed by using a 405 nm laser diode source, whose output beam was pulse amplitude-modulated at 1.33 kHz by means of a laser driver. The electrical signal out of the GFETs (in a common source amplifier configuration) was measured using a lock-in amplifier synchronized to the same reference frequency of the laser driver. Thi…

Poly(alkoxyphenylene-thienylene) Langmuir-Schäfer thin-films for advanced performance transistors

2005

Solution processed Langmuir-Scha ̈fer and cast thin films of regioregular poly(2,5-dioctyloxy-1,4- phenylene-alt-2,5-thienylene) are investigated as transistor active layers. The study of their field-effect properties evidences that no transistor behavior can be seen with a cast film channel material. This was not surprising considering the twisted conformation of the polymer backbone predicted by various theoretical studies. Strikingly, the Langmuir-Scha ̈fer (LS) thin films exhibit a field-effect mobility of 5 × 10-4 cm2/V‚s, the highest attained so far with an alkoxy-substituted conjugated polymer. Extensive optical, morphological, and structural thin-film characterization supports the a…